Artificial leg



J. NEVI N.

ARTIHCIAL LEG.

APPLICATION man FEB.13. 1919'.

Patented Mar. 22, 1921.

2 SHEETS-SHEET 1.

J. NEVIN.

AHTIFICIAL LEG.

APPLICATION FILED FEB-13,1919.

Patented Mar. 22, 1921.

2 SHEETSSHEET 2.

Ina enter,

JAMES NEVIN, OF THOROLD, ONTARIO, CANADA.

ARTIFICIAL LEG.

Specification of Letters Patent.

Patented Mar. 22, 1921.

Application filed February 13, 1919. Serial No. 276,765.

To all whom cit may concern:

Be it known that 1, James NEVIN, a subject of the King of Great Britain, and resident of the town of Thorold, in the county of l/Velland, Province of Ontario, Canada, have invented certain new and useful Improvements in Artificial Legs, of which the following is a specification.

This invention relates to artificial legs adapted for either above or below the knee amputations, and my object is to devise a simple and strong construction which will give a more natural and easier action than the present type of leg and which, therefore will give greater comfort to the wearer.

I attain my object by means of an improved ankle joint construction and by so arranging the joints of the leg that, when the wearer is standing upright with all parts of the artificial leg free to assume their normal positions, the axis of the knee joint is forward of the vertical plane in which the axis of the ankle joint lies and a spring is provided tending to resist the bend ing at the knee joint when the wearers weight is on the artificial leg.

The constructions referred to and. other improvements in the details of construction are illustrated in the accompanying drawings in which" t Figure 1 is a vertical section of an artificial leg constructed in accordance with my invention, the leg being shown in the position it assumes when the wearer is standing upright on both feet;

Fig. 2 a similar view showing the leg bent at the knee joint in the position it assumes when the wearer is sitting;

Fig. 3 a side elevation showing a modified form of the spring connection between the thigh and shank portions of the leg;

Fig. 4 a similar view showing a furtht-zr modification such as used with below the knee amputations; i

Fig. 5 a rear view, partly brokenaway, of parts shown in Fig. 3. r i j In the drawings like numerals of reference indicate corresponding parts in the different figures. l i

Referring particularly to Figs. 1 and 2, 1 is the thigh portion of the leg, 2 the shank portion and 3 the foot. These parts may be constructed in any ordinary manner known to the art- The foot is pivotallyconnected withthe shank portion by means of the pivot pin 4:, which is secured to one of the parts which it connects and passes through a vertical slot formed in the other. Preferably the slot 5 is formed within the sides of the lower parts of the side irons 6 of the shank port1on. Both in front of and behind the plvot p111 opposed shoulders 7 are formed on the foot and shank portions, and between those shoulders are placed rubber cushions 8. To hold the parts in contact, which is necessary in view of the fact that the pivot pin works in a slot, I provide the flexible cord 9, which passes over a guide roller 10 journaled in the shank portion. The ends of this cord are secured to the front portion and spring tension means are provided for this cord or connector. In the preferred arrangement, each end of the cord has a metal end piece 11 secured thereto, which is threaded to. receive a nut 12. The cord passes through alined holes in the shank portion cushions and foot, which holes open into recesses formed in the under side of the foot to receive coil springs 13, which springs engage the shoulders 14 formed at the bottoms of the recesses and the nuts 12. By means of these nuts any suitable tension can be given to the cord. With this arran ement the necessary limited and elastically cushioned rocking movement is provided for the ankle joint, and further a cushioning effect is obtained when the wearer is standmg upr1gl1t owlng to the fact that the plvot pin operates in a vertical slot. Under all conditions the parts are held in proper contact by the cord 9. V j

The vertical line drawn in Fig. 1 through the ankle joint is assumed to lie in a vertical plane in which lies the center of gravity of the body of the wearer when he is standing erect on both feet. It will beunoted that under these conditions. the axis of the pivot pin 15 which forms the knee joint lies in front of this vertical line.' The result is that the weight of the wearer. tends to flex the knee joint, which is exactly the opposite arrangement to that commonly adopted in which the knee joint under these conditions thigh portion of the leg.

back as shown in dotted this movement, and to obtain the advantages I desire such limiting means must be resilient 'in their character.

In Figs. 1 and 2 I show :an-arrangement, which may be considered as more or less diagramniatical, for the purposes of illustration. A coil spring 16 is carried by a bracket within the shank portion of the leg A connecting'rod 17 is pivotally connected with the thigh'portion of the leg and has an end 18 adapted to engage the upper end of the coil spring. This connecting rod passes through a slide 19, which passes throughthe back of the-shell-of the shank portion of the leg and-has a button securedthereto.

As will be seen from the drawings, the end of the connecting rod may by the operation of the slide be either brought into engagement with the upper end of" the spring 16-01 pushed out of engagement therewith. iVhen the parts are in the position shown in Fig. 1', the necessary spring cushion between the thigh and the shank portion of the leg is provided. When the wearer desires to sit downythe connecting rod maybepushed forward as shown in Fig. 2, when the leg willfi-ex unrestrained at'the knee joint.

In 'Fig. i I show-an arrangement which is'best adapted forbelow-the-knee amputations when it is not possible to place any mechanism within the shell or" the shank portion of the leg. In this case the thigh portion terminates in the side irons 20 pivoted on the-shank portion of the leg. A yoke-21 extends forwardly from these side irons and 'is provided with an eye 22 to which is connected a cord or wire 23, which passes through and is suitably secured to the lower endof a'compression coil spring 24-. A fork 25 is secured to the front of the shank portion ofthe leg and with this fork the upper end-of thecoil spring 24 is en gaged when the wearer is walking. hen the wearer desires to sit down, the coil spring-is readily disengaged from the fork and'the leg lett'free to flex at-tl e knee joint.

I find that with the constructions described the leg is much more comfortable to use and approximates very much more closely to theaction of the natural leg than other artificial legs which I have used or with which I am acquainted.

In F ig. 3 l'show a preferred construction of the spring connection. The spring 26 is of the semielliptic type and its ends are slidalole on a guide plate 27 secured to the y In the shank portion of the leg is journaled a shaft 28 on which is secured an arm 29 adapted to be brought into engagement with the spring as shown in full lines 'in 'Fig. 3, or tipped lines when the .wearer of the leg desires to sit :down. To

operatethe shaft I provide atone end a lever 30. Thi slever-is'provided with'a lug 31 inch is engageable by the slip pin 53:2 movable in guidelugs 33 formed in a plate secured to the outside of the shell at the shankportion oizthe leg. By moving this slip pin lengthwise, the lever arm :30 is releasedor engaged and held as may be desired.

It-will be found that the whole action of my leg is entirely diiierent from the ordinary leg in which the knee is rigid and non-resilient when the wearers weight is upon it, and which, therefore, produces a disagreeable drag upon the stump when lhe legis brought up from behind. \Vhcn the wearers weight is on my leg, the leg automatically liexes slightly both at the ankle and .knee and automatically extends when the wearers weight is taken oil, thus making the action of bringing theleg forward more easy and natural, involving less abnormal muscular action on the part of the stump.

'lVhat I claim as my invention is:

1. An artificial leg jointed at the knee and the ankle, the axis of said knee joint being forward o'f'thc center oi gravity of the wearers bodyfand manually releasable cushioning means normallyelastically limiting the bendingat'the knee oint when the wearers weight is on the leg.

2. An artificial .leg jointed at the knee and-theankle, the axis of said knee joint being forward 'of'the center of gravity of the wearers body, in combination with a manually releasable spring connection betweenthe parts of'the leg above and below the knee joint tending to resist bending at the knee joint and to support-the wcarers weight.

3. An artificial leg jointed at the "knee and the ankle, the axis of:said knee joint being forwardof the center of gravity of the wearers body, 'in combination with a manually releasable spring connection betwcen'theparts of the leg above and below the knee joint tending to resist bending at theknee jointand to support the wearers weight, and spring means permitting a limited rocking movement of the foot on the ankle joint.

21. In an artificial leg, the col'nbination of a 'i'oot; a shank portion; a. pivot pin secured to one of said parts and passing through a vertical slot formed in the other part to form an ankle joint; opposed shoulders formed on said parts both in front ofand behind the pivot pin; resilient cushions fitted between said shoulders; and flexible spring means tendingto draw the foot and shank portions together without interference with therocking movement of the foot on the shank;

5. In an artificial leg, the combination of a foot; a shank portion; a pivot pin secured to "one of said parts and passing through a vertical slot formed in the other part to form an ankle joint; opposed shoulders formed on said parts both-in front of and behind the pivot pin; resilient cushions .fitted between said shoulders; a flexible connector engaged at its ends with the foot; a guide on the shank portion over which the connector is led; and spring tensioning means for the connector.

6. An artificial leg jointed at the knee and the ankle, the axis of said knee joint being forward of the center of gravity of the wearers body, in combination with a compression spring and a manually releasable member movable into and out of operative engagement with said. spring.

7. An artificialleg jointed at the knee and the ankle, the axis of said knee joint being forward of the center of gravity of the wearers body, in combination with a compression spring, a shaft carried by part of the leg, an arm carried by said shaft and movable into and out of cooperative engage ment with said spring, and manually operating means for releasably locking the arm in engagement with the spring.

8. An artificial leg jointed at the knee and the ankle, the axis of said knee joint being forward of the center of gravity of the wearers body, in combination with a compression spring, a shaft suitably journaled, an arm secured to said shaft and movable by the rocking of the shaft into and out of cooperative engagement with the spring, an arm secured to the shaft outside the leg, and releasable locking means operated by said arm.

Signed at Thorold this 28th day of J anuary, A. D. 1919.

JAMES NEVIN. Witnesses:

JOSEPH J. DOHERTY, WVILLIAM A. ARMSTRONG. 

